Insulin-like growth factor binding proteins in development

IGFBPs regulate growth and development by regulating IGF transport to tissues and IGF bioavailability to IGF receptors at cell membrane level. IGFBP excess leads predominantly to inhibition of IGF action and growth retardation with impaired organogenesis. Absence of human and also mouse ALS leads to decreased IGF-I levels in circulation and causes mild growth retardation. Although IGFBP KO mice demonstrate relatively minor phenotypes, the possibility of compensatory mechanisms that mask the phenotypic manifestation of lack of individual binding proteins needs to be further investigated. Recent studies of hepatic regeneration in IGFBP-1 KO mice and also with mutant IGFBP-3 Tg mice provide some limited support for the existence of IGF-independent mechanism of action in vivo.

The role of endogenous hormones in the etiology and prevention of breast cancer: the epidemiological evidence

Breast cancer is the most common cause of cancer death in women worldwide. Rates vary about fivefold around the world, but they are increasing in regions that until recently had low rates of disease. Despite the numerous uncertainties surrounding the etiology of breast cancer, intensive epidemiological, clinical, and genetic studies have identified a number of biological and social traits as risk factors associated with breast cancer. Principal among them is the evidence of BRCA1 and BRCA2 susceptibility genes, familial history of breast cancer, age, higher socioeconomic status, ionizing radiation, tallness in adult life, alcohol consumption, and a variety of hormone and metabolic factors. Among the hormonal influences, a relevant etiological function has been ascribed to unopposed exposure to elevated levels of estrogens and androgens. In addition, new epidemiologic evidence has indicated that among the metabolic factors, glucose metabolism, hyperinsulinemic insulin resistance, and insulin-like growth factor bioavailability may also play a role in breast cancer. These endocrine and metabolic factors may represent future targets for breast cancer prevention.

Prevention of diabetes in non-obese diabetic (NOD) mice by short-term and high-dose IGF-I treatment

This report describes the results of IGF-I treatment in a NOD mouse colony with a high incidence of overt diabetes. The animals were treated with IGF-I 17.9 nmol/day at 28-41 days of age and 35.9 nmol/day at 42-69 days of age and observed up to 280 days of age. Three of 12 (25%) IGF-I-treated animals developed diabetes compared with 8 of 11 (73%) controls (P < 0.05). The severity of insulitis at the conclusion of the follow-up was less pronounced in non-diabetic treated animals than in non-diabetic controls. These data support previous findings that IGF-I treatment protects the pancreatic beta-cells from destruction by diabetic autoimmunity in NOD mice.